This invention relates generally to methods and apparatus for coronary imaging, and more particularly to methods and apparatus for computed tomographic (CT) imaging of specific artery branches with reduced motion artifacts.
Computed tomographic (CT) imaging and magnetic resonance imaging (MRI) can be utilized to visualize coronary arteries, which are very tiny structures. However, visualization of these structures is difficult, because different coronary arteries are subject to different motions throughout a cardiac cycle. For example, the right coronary artery (RCA) remains on a single plane and undergoes large displacements. The left anterior descending (LAD) vessel, on the other hand, lies on a curved surface and its branches follow different motion patterns. Known electrocardiograph (EKG) driven reconstruction methods and apparatus do not take these variations into account, so it has been difficult to achieve optimum visualization of at least some coronary arteries.
In one aspect, a method for imaging a desired coronary artery or desired portion thereof utilizing a computed tomography (CT) imaging system is provided. The imaging system includes a rotating gantry, a detector array on the rotating gantry, and a radiation source on the rotating gantry configured to project a beam of radiation towards the detector array through a patient""s heart. The method includes scanning a volume of the patient""s heart with the CT imaging system to acquire projection data, the volume including at least a first desired coronary artery branch segment and a second desired coronary artery branch segment, and the acquired projection data including a first projection dataset representing the first desired coronary artery branch segment acquired during the first desired cardiac phase of a plurality of cardiac cycles of the patient and a second projection dataset representing the second desired coronary artery branch segment acquired during the second desired cardiac phase of a plurality of cardiac cycles of the patient, and selecting a first cardiac phase corresponding to a low motion period of the first desired coronary artery branch segment of a patient""s heart and a different, second cardiac phase corresponding to the second, different desired coronary artery branch segment of the patient""s heart. The method also includes reconstructing a first 2D image of the first desired coronary artery branch segment utilizing the first projection dataset acquired during the first desired cardiac phase of a plurality of cardiac cycles to reduce motion artifacts of the first desired coronary artery branch segment, reconstructing a second 2D image of the second desired coronary artery branch segment utilizing the second projection dataset acquired during the second desired cardiac phase of a plurality of cardiac cycles to reduce motion artifacts of the second desired coronary artery branch segment, reconstructing at least one 3D image of the coronary artery utilizing the first 2D image and the second 2D image.
In another aspect, a computed tomography (CT) imaging system having a rotating gantry, a detector array on the rotating gantry, and a radiation source on the rotating gantry configured to project a beam of radiation towards the detector array through a patient""s heart is provided. The system is configured to scan a volume of the patient""s heart to acquire projection data, the volume including at least a first desired coronary artery branch segment and a second desired coronary artery branch segment, the acquired projection data including a first projection dataset representing the first desired coronary artery branch segment acquired during the first desired cardiac phase of a plurality of cardiac cycles of the patient and the second projection dataset representing the second desired coronary artery branch segment acquired during the second desired cardiac phase of a plurality of cardiac cycles of the patient and select a first cardiac phase corresponding to a low motion period of the first desired coronary artery branch segment of the patient""s heart and a different, second cardiac phase corresponding to the second, different desired coronary artery branch segment of the patient""s heart. The system is also configured to reconstruct a first 2D image of the first desired coronary artery branch segment utilizing the first projection dataset acquired during the first desired cardiac phase of a plurality of cardiac cycles to reduce motion artifacts of the first desired coronary artery branch segment, reconstruct a second 2D image of the second desired coronary artery branch segment utilizing the second projection dataset acquired during the second desired cardiac phase of a plurality of cardiac cycles to reduce motion artifacts of the second desired coronary artery branch segment, and reconstruct at least one 3D image of the coronary artery utilizing the first 2D image and the second 2D image.
In a further aspect, a machine readable medium having instructions recorded thereon is provided. The machine readable medium is configured to instruct a computer to scan a volume of the patient""s heart to acquire projection data, the volume including at least a first desired coronary artery branch segment and a second desired coronary artery branch segment, the acquired projection data including a first projection dataset representing the first desired coronary artery branch segment acquired during the first desired cardiac phase of a plurality of cardiac cycles of the patient and the second projection dataset representing the second desired coronary artery branch segment acquired during the second desired cardiac phase of a plurality of cardiac cycles of the patient and select a first cardiac phase corresponding to a low motion period of the first desired coronary artery branch segment of the patient""s heart and a different, second cardiac phase corresponding to the second, different desired coronary artery branch segment of the patient""s heart. The machine readable medium is also configured to instruct the computer to reconstruct a first 2D image of the first desired coronary artery branch segment utilizing the first projection dataset acquired during the first desired cardiac phase of a plurality of cardiac cycles to reduce motion artifacts of the first desired coronary artery branch segment, reconstruct a second 2D image of the second desired coronary artery branch segment utilizing the second projection dataset acquired during the second desired cardiac phase of a plurality of cardiac cycles to reduce motion artifacts of the second desired coronary artery branch segment, and reconstruct at least one 3D image of the coronary artery utilizing the first 2D image and the second 2D image.